Second Rhagophthalmid Luciferase Cloned from Chinese Glow‐worm Menghuoius giganteus (Rhagophthalmidae: Elateroidea)

A bio-inspired co-simulation crawling robot enabled by a carbon dot-doped dielectric elastomer

Flexible actuation materials play a crucial role in biomimetic robots. Seeking methods to enhance actuation and functionality is one of the directions in which actuators strive to meet the high-performance and diverse requirements of environmental conditions. Herein, by utilizing the method of adsorbing N-doped carbon dots (NCDs) onto SiO2 to form clusters of functional particles, a NCDs@SiO2/PDMS elastomer was prepared and its combined optical and electrical co-stimulation properties were effectively harnessed to develop a biomimetic crawling robot resembling Rhagophthalmus (firefly). The introduction of NCDs@SiO2 cluster particles not only effectively improves the mechanical and dielectric properties of the elastomer but also exhibits fluorescence response and actuation response under the co-stimulation of UV and electricity, respectively. Additionally, a hybrid dielectric elastomer actuator (DEA) with a transparent SWCNT mesh electrode exhibits two notable advancements: an 826% increase in out-of-plane displacement under low electric field stimulation compared to the pure matrix and the ability of NCDs to maintain a stable excited state within the polymer for an extended duration under UV-excitation. Simultaneously, the transparent biomimetic crawling robot can stealthily move in specific environments and fluoresce under UV light.

Cloning and characterization of luciferase from an Asian firefly Pygoluciola qingyu and its comparison with other beetle luciferases

The bioluminescence system of luminescent beetles has extensive applications in biological imaging, protein labeling and drug screening. To explore wild luciferases with excellent catalytic activity and thermal stability, we cloned the luciferase of Pygoluciola qingyu, one species living in areas of high temperature and with strong bioluminescence, by combining transcriptomic sequencing and reverse transcription polymerase chain reaction (RT-PCR). The total length of luciferase gene is 1638 bp and the luciferase consists 544 amino acids. The recombinant P. qingyu luciferase was produced in vitro and its characteristics were compared with those of eight luciferases from China firefly species and two commercial luciferases. Compared with these luciferases, the P. qingyu luciferase shows the highest luminescence activity at room temperature (about 25-28 ℃) with similar KM value for D-luciferin and ATP to the Photinus pyralis luciferase. The P. qingyu luciferase activity was highest at 35 ℃ and can keep high activity at 30-40 ℃, which suggests the potential of P. qingyu luciferase for in vivo and cell application. Our results provide new insights into P. qingyu luciferase and give a new resource for the application of luciferases.

Multiple Origins of Bioluminescence in Beetles and Evolution of Luciferase Function

Bioluminescence in beetles has long fascinated biologists, with diverse applications in biotechnology. To date, however, our understanding of its evolutionary origin and functional variation mechanisms remains poor. To address these questions, we obtained high-quality reference genomes of luminous and nonluminous beetles in 6 Elateroidea families. We then reconstructed a robust phylogenetic relationship for all luminous families and related nonluminous families. Comparative genomic analyses and biochemical functional experiments suggested that gene evolution within Elateroidea played a crucial role in the origin of bioluminescence, with multiple parallel origins observed in the luminous beetle families. While most luciferase-like proteins exhibited a conserved nonluminous amino acid pattern (TLA346 to 348) in the luciferin-binding sites, luciferases in the different luminous beetle families showed divergent luminous patterns at these sites (TSA/CCA/CSA/LVA). Comparisons of the structural and enzymatic properties of ancestral, extant, and site-directed mutant luciferases further reinforced the important role of these sites in the trade-off between acyl-CoA synthetase and luciferase activities. Furthermore, the evolution of bioluminescent color demonstrated a tendency toward hypsochromic shifts and variations among the luminous families. Taken together, our results revealed multiple parallel origins of bioluminescence and functional divergence within the beetle bioluminescent system.

A new species of Rhagophthalmus Motschulsky, 1854 (Coleoptera, Rhagophthalmidae) from Laos represents the smallest known member of the genus

Rhagophthalmus Motschulsky, 1854 is the most speciose genus in Rhagophthalmidae, distributed in the region encompassing South, East, and Southeast Asia. Here, we describe R.nanussp. nov. from the Houaphanh Province of eastern Laos, which represents the smallest known species in Rhagophthalmus and one of the smallest in Rhagophthalmidae. We compare it with the morphologically similar and geographically close congeners and provide a preliminary identification key to adult males of Rhagophthalmus species from mainland Southeast Asia. Additionally, we discuss the morphology and variability of male genitalia within Rhagophthalmus.

Rhagophthalmidae Olivier, 1907 (Coleoptera, Elateroidea): described genera and species, current problems, and prospects for the bioluminescent and paedomorphic beetle lineage

Rhagophthalmidae are a small beetle family known from the eastern Palaearctic and Oriental realms. Rhagophthalmidae are closely related to railroad worms (Phengodidae) and fireflies (Lampyridae) with which they share highly modified paedomorphic females and the ability to emit light. Currently, Rhagophthalmidae include 66 species classified in the following 12 genera: Bicladodrilus Pic, 1921 (two spp.), Bicladum Pic, 1921 (two spp.), Dioptoma Pascoe, 1860 (two spp.), Diplocladon Gorham, 1883 (two spp.), Dodecatoma Westwood, 1849 (eight spp.), Falsophrixothrix Pic, 1937 (six spp.), Haplocladon Gorham, 1883 (two spp.), Menghuoius Kawashima, 2000 (three spp.), Mimoochotyra Pic, 1937 (one sp.), Monodrilus Pic, 1921 (two spp. in two subgenera), Pseudothilmanus Pic, 1918 (two spp.), and Rhagophthalmus Motschulsky, 1854 (34 spp.). The replacement name Haplocladongorhami Kundrata, nom. nov. is proposed for Diplocladonhasseltii Gorham, 1883b (described in subgenus Haplocladon) which is preoccupied by Diplocladonhasseltii Gorham, 1883a. The genus Reductodrilus Pic, 1943 is tentatively placed in Lampyridae: Ototretinae. Lectotypes are designated for Pseudothilmanusalatus Pic, 1918 and P.marginalis Pic, 1918. Interestingly, in the eastern part of their distribution, Rhagophthalmidae have remained within the boundaries of the Sunda Shelf and the Philippines demarcated by the Wallace Line, which separates the Oriental and Australasian realms. This study is intended to be a first step towards a comprehensive revision of the group on both genus and species levels. Additionally, critical problems and prospects for rhagophthalmid research are briefly discussed.

Molecular cloning, characterization, and evolution analysis of the luciferase genes from three sympatric sibling fireflies (Lampyridae: Lampyrinae, Diaphanes)

Firefly adult bioluminescence functions as signal communication between sexes. How sympatric sibling species with similar glow pattern recognize their conspecific mates remains largely unknown. To better understand the role of the luciferases of sympatric fireflies in recognizing mates, we cloned the luciferase genes of three sympatric forest dwelling fireflies (Diaphanes nubilus, Diaphanes pectinealis, and Diaphanes sp2) and evaluated their enzyme characteristics. Our data show that the amino acid (AA) sequences of all three luciferases are highly conserved, including the identities (D. nubilus vs D. pectinealis: 99%; D. nubilus vs Diaphanes sp2: 98.5%; D. pectinealis vs Diaphanes sp2: 99.4%) and the protein structures. Three recombinant luciferases produced in vitro all possess significant luminescence activity at pH 7.8, and similar maximum emission spectrum (D. nubilus: 562 nm; D. pectinealis and Diaphanes sp2: 564 nm). They show the highest activity at 10 °C (D. pectinealis, Diaphanes sp2) and 15 °C (D. nubilus), and completely inactivation at 45 °C. Their KM for D-luciferin and ATP were 2.7 μM and 92 μM (D. nubilus), 3.7 μM and 49 μM (D. pectinealis), 3.5 μM and 46 μM (Diaphanes sp2). Phylogenetic analyses support that D. nubilus is sister to D. pectinealis with Diaphanes sp2 at their base, which further cluster with Pyrocoelia. All combined data indicate that sympatric Diaphanes species have similar luciferase characteristics, suggesting that other strategies (e.g., pheromone, active time, etc.) may be adopted to recognize mates. Our data provide new insights into Diaphanes luciferases and their evolution.

Luciferase isozymes from the Brazilian Aspisoma lineatum (Lampyridae) firefly: origin of efficient pH-sensitive lantern luciferases from fat body pH-insensitive ancestors

Firefly luciferases usually emit green-yellow bioluminescence at physiological pH values. However, under acidic conditions, in the presence of heavy metals and, at high temperatures they emit red bioluminescence. To understand the structural origin of bioluminescence colors and pH-sensitivity, about 20 firefly luciferases have been cloned, sequenced and investigated. The proton and metal-binding site responsible for pH- and metal sensitivity in firefly luciferases was shown to involve the residues H310, E311 and E354 in firefly luciferases. However, it is still unclear how and why pH-sensitivity arose and evolved in firefly luciferases. Here, we cloned and characterized two novel luciferase cDNAs from the fat body and lanterns of the Brazilian firefly Aspisoma lineatum. The larval fat body isozyme (AL2) has 545 residues, and displays very slow luminescence kinetics and a pH-insensitive spectrum. The adult lantern isozyme (AL1) has 548 residues, displays flash-like kinetics and pH and metal sensitive bioluminescence spectra, and is at least 10 times catalytically more efficient than AL2. Thermostability and CD studies showed that AL2 is much more stable and rigid than the AL1 isozyme. Multialignment and modelling studies show that the E310Q substitution (E310 in AL2 and Q310 in AL1) may have been critical for the origin of pH-sensitivity in firefly luciferases. The results indicate that the lantern efficient flash-emitting pH-sensitive luciferases arose from less efficient glow-type pH-insensitive luciferases found in the fat body of ancestral larval fireflies by enzyme structure flexibilization and substitution at position 310.